The present invention relates to a method for controlling the tape affixing direction of an automatic tape affixing apparatus for automatically affixing a tape of composite material on the surface of an adhesion form having various contours to make a lamination of the tape.
In recent years, lightweight plate materials have been produced from a tape of composite material, i.e. a tape prepared by impregnating carbon fiber, aramid fiber or like reinforcing fiber with a thermosetting resin, by affixing the tape on the surface of an adhesion form (body) having specified contours to make a lamination, and thereafter subjecting the lamination to a curing treatment with application of heat and pressure. Japanese Unexamined Patent Application No. 58-45057, for example, discloses a method for automatically affixing such a tape of composite material. With this method, the tape is continuously paid off from a reel and pressed against the surface (curved surface) of an adhesion form with a press roller, the press roller is moved along a predetermined path to successively affix tape portions without leaving a clearance therebetween, and the tape affixing direction is changed from layer to layer, whereby a lamination is obtained.
In the above-mentioned method, the tape consists of a filament tape and a backing paper. In affixing the tape, the filament tape is affixed on the adhesion form while the backing paper is taken up by another reel. However, it can not be expected that long fibers used for the filament tape stretches and contracts following the surface contour. Consequently, when the tape is affixed on a conical projection 80 on an adhesion form 8 as shown in FIG. 5, natural path 100 in which the tape is affixed without wrinkles changes before and after the conical projection 80.
On the other hand, it is required that tape strips be affixed with a minute clearance therebetween by pressing the tape strips against the surface of the adhesion form or curved surface while moving a presser roller along the natural path. If the actual moving path of the presser roller is different from the natural path, the tape may deviate widthwise at the presser roller portion, i.e., sidewise deviation or wrinkles occur in a worse case. Accordingly, if the tape deviates sidewise, a minute clearance will not be maintained between tape portions but a large clearance occurs, or conversely, tape strips overlap one another, further the tape is locally unpressed by the presser roller and is then incompletely adhered. It could be seen that even if such incomplete lamination is treated for curing, a plate can not be obtained which has a specified quality, for example, a necessary strength.
An actual adhesion form has a complicated three-dimensional contour. Accordingly, the tape affixing course is determined after the natural path is calculated as follows.
When the tape affixing course is determined based on the natural path with respect to an adhesion form having two intersecting planes as shown in FIG. 6, any one of the following conditions is required to affix a tape 10 across an intersecting line of the two planes or ridge without wrinkles;
(a) respective lengths l.sub.1 and l.sub.2 of the opposite sides of the tape 10 are the same;
(b) incident angles .theta..sub.1 and .theta..sub.2 of the tape 10 with respect to the ridge are the same.
In the case of calculating the natural path based on the condition (a), the tape course is difficult to determine at one calculation. There is no other way than that the tape course is approximately found out by repeated calculations. This means that the processing time of a computer becomes longer and that only approximate course can be obtained, in other words, accurate course can not be obtained. Additionally, since an actual adhesion form has complicated three-dimensional contours and configuration within both sides of the tape is ignored in the above-mentioned calculation based on the condition (a), an optimum natural path can not be obtained. Thus, it is inappropriate to calculate the natural path under the condition (a).